A technique for enhancing confidentiality of stored data has conventionally been known.
For example, Japanese Patent Laying-Open No. 2008-204507 (PTD 1) describes a scheme for a semiconductor device, for write in a data storage unit after scramble processing is performed onto write data by using scramble information generated by a random number generation unit. Since scramble information is stored in an SRAM representing a volatile memory, scramble information is erased at the time when power is turned off even though stored data remains in the data storage unit in a power off state of the semiconductor device, and hence stored data in the data storage unit can no longer correctly be read. Thus, confidentiality of stored data can be improved.
Japanese Patent Laying-Open No. 2010-277584 (PTD 2) also describes a non-volatile storage device which subjects write data to scramble processing, writes the data, reads the data, and thereafter subjects the data to descramble processing.